- Preheat oven to 350 degrees Fahrenheit. Heat a large oven-safe pot over high heat.

- Season the lamb shanks with salt. Add oil to the pan and brown the shanks on all sides. Once each of the shanks has been nicely browned, transfer them to a plate and set aside.

- Meanwhile, puree the onion, carrot, celery, and garlic in a food processor. Add in tomato paste. Put this puree into the pan you used to brown the shanks and sauté for 3 to 5 minutes. Stir in the cranberry juice.

- Return lamb shanks to the mixture. Top with rosemary sprigs and place the lid on. Cook in the 350-degree oven for 2 1/2 to 3 hours, until lamb is fork tender. Remove lid during last 30 minutes of cooking to allow shanks to brown.